Effects of Three-Dimensionality and Nonlinearity on the Dynamic and Seismic Behavior of Cable-Stayed Bridges

The cases of multiple-support as well as uniform seismic excitations of these long and flexible structures are considered; furthermore, effects of the nondispersive travelling, seismic-wave on the bridge response are studied. Different sources of nonlinearity for such bridges are included in the analysis using the large deflection theory. A tangent stiffness iterative procedure is utilized in the analysis to capture the nonlinear seismic response. Numerical examples are presented in which a comparison between a linear earthquake-response analysis (based on the utilization of the tangent stiffness matrix of the bridge at the dead-load deformed state which is obtained from the geometry of the bridge under gravity load conditions), and a nonlinear earthquake-response analysis using the step-by-step integration procedure is made. In these examples, two models having center (or effective) spans of 1100 ft (335. 5m) and of 2200 ft (671 m) are studied; this range covers both present and future designs.